When customers buy a moissanite pendant, they do not actually care about carat weight. They care about how big the stone looks on their collarbone, how it photographs, and whether it reads as generous next to a friend's diamond. But because the entire US jewelry market has been trained on carats, your customers will ask in carats, and your product pages will rank better if you answer in millimeters. For independent jewelers sourcing moissanite pendants factory-direct from Wuzhou, a clear carat-to-millimeter reference is one of the most useful internal tools you can build. This guide covers the round sizes you will source most often, how other shapes convert, and how to talk about size honestly without overpromising.
Why moissanite is not graded in carats the way diamond is
Moissanite is denser than diamond. A round moissanite of 6.5 mm diameter weighs roughly 1.0 carat equivalent, but the actual carat weight of that moissanite is lower. Because the gem is sold primarily on visual appearance rather than on weight, reputable factories label it by millimeter diameter rather than by carat. When a supplier quotes you a "1-carat moissanite pendant," confirm the actual mm diameter; the visual size is what your customer will judge, and the mm figure is what determines the setting, the bail, and the chain gauge.
Round brilliant moissanite size chart
5 mm (roughly 0.5 carat equivalent)
A 5 mm round is the entry-size solitaire pendant. It reads delicate on a 16- to 18-inch chain and is the standard for bridal-party gifts, everyday wear, and first-pendant purchases. It is small enough to sit comfortably under a crew neckline and light enough to pair with a thin cable chain. This is the highest-volume SKU for most boutiques.
6.5 mm (roughly 1.0 carat equivalent)
The 6.5 mm round is the workhorse. It reads as a serious solitaire pendant, photographs beautifully, and is large enough to be noticed without being oversized on a woman's collarbone. This is the size most customers picture when they say "a one-carat pendant." It pairs naturally with a four-prong setting and a 1.2 to 1.5 mm cable chain.
7.5 mm (roughly 1.5 carat equivalent)
A 7.5 mm round is a statement pendant. It is the size customers choose for anniversaries, milestone birthdays, and formal occasions. It needs a reinforced bail, a six-prong or bezel setting, and a slightly heavier chain (1.5 to 2 mm) to carry the weight without looking flimsy. Stock this size in lower quantities because it is a more deliberate purchase.
8 mm and above (2 carat equivalent and beyond)
At 8 mm and larger, the pendant becomes a fashion-forward piece rather than an everyday one. The stone itself begins to show the inherent gray or green undertones that moissanite can exhibit at larger sizes, so it is especially important to specify DEF-grade material for these pieces. These sizes are best ordered to order rather than carried in inventory.
Oval, pear, and cushion conversions
Shapes other than round are labeled by two dimensions. An oval moissanite pendant is commonly 7 by 5 mm or 8 by 6 mm, which visually approximates a 1-carat and 1.5-carat round respectively. A pear or marquise of similar mm dimensions reads longer and slimmer than a round. When you source ovals and pears, always specify both mm dimensions rather than a carat equivalent, because the visual length is what the customer reacts to. Cushion cuts are typically labeled by width in millimeters; a 6.5 mm cushion reads slightly smaller than a 6.5 mm round because of the cut corners.
How size reads on the body
A pendant that looks large in a product photo can look modest on a customer's neck, and vice versa. The rule of thumb for US retail is that a 6.5 mm round on an 18-inch chain is the most universally flattering combination. Customers with longer necks or smaller collarbones can carry a 7.5 mm pendant; customers who prefer minimal jewelry will prefer 5 mm. When you merchandise, display these three sizes side by side on a neck form so the customer can see the difference at a glance rather than relying on a millimeter number.
Setting sizes and metal consumption
The center-stone diameter drives the setting size, which drives the weight of silver used. A 5 mm setting uses a small amount of metal; a 7.5 mm setting uses roughly twice as much silver and requires a larger prong head. When you compare factory quotes, look at the total piece weight in grams as well as the stone size; a pendant that is underweight for its stone size will look thin and cheap next to a properly weighted setting.
Pricing logic and margin
Moissanite pendant pricing scales with stone diameter, but not linearly. The jump from 5 mm to 6.5 mm is modest; the jump from 6.5 mm to 7.5 mm is larger because DEF-grade material becomes more scarce at larger diameters. Build your retail price ladder around that curve: price the 5 mm as an entry gift, the 6.5 mm as your bestseller, and the 7.5 mm as a premium statement piece. Do not spread yourself across every intermediate size; three to four round sizes cover most demand.
Customer expectations and honest labeling
Never list a moissanite pendant as "1-carat diamond" or imply a weight that the stone does not have. List the mm diameter, describe the stone as DEF-color moissanite, and provide the "approximate diamond equivalent" only as a reference. Honest labeling builds repeat customers; misleading labels build returns and FTC complaints. Most customers who buy moissanite do so because they understand the value, and they will respect a listing that is precise about size.
Reordering strategy
Once you have six to twelve months of sales data, reorder by size rather than by style. Most boutiques find that 5 mm and 6.5 mm rounds make up 70 to 80 percent of pendant sales, while 7.5 mm and larger sizes move in smaller volume. Concentrate your open-to-buy on the sizes that actually sell, and order larger sizes on demand rather than tying up capital in slow inventory.
Photographing size honestly
Size is the hardest product attribute to communicate online, because every photo is taken at a slightly different focal length. Reference your mm chart in every listing: include a scale shot of the pendant next to a coin, a hand, or a ruler, and show the stone worn on a model whose neck is average rather than slender. Customers who feel misled about size are the most likely to return the piece, while customers who receive exactly the size they expected become repeat buyers. The mm chart on your product page is itself a trust signal, and it is one of the few places where being precise about numbers improves conversion rather than slowing it down.
Conclusion
A moissanite pendant is bought for its visual size, and the millimeter is the honest unit that describes it. By sourcing in 5 mm, 6.5 mm, and 7.5 mm rounds, specifying exact two-dimensional sizes for ovals and pears, and labeling each piece by mm rather than by carat equivalent, you give your customers a clear expectation and your store a defensible price ladder. The size chart is not just a buying tool; it is the product page copy that helps your pendant section rank and convert.